[robocup-small] Minor Rules Changes and Proposals (by B-Smart)

[Ulfert]

*sorry for length*

Hi there robocuppers

As referees in the last games of RoboCup 2007 our team experienced some of the
rules we have found out to be unclear, not formulated at all or just not quite
the way it could be near perfect. Therefore we discussed about some changes and
found the following solutions.

We also talked about where we see the SSL in about two years and propose some
changes in the system. They are put as proposals for challenges so everybody who
wants to develop such things ma have some points to focus on or at least to notice.

1. Proposal for rules change for "Competition Rules":

Do "Competition Rules" for RoboCup 2007 and 2008 exist for SSL? In the
official rules those Competition Rules are mentioned several times (Laws 7 and
10). As on the official site of SSL
(http://small-size.informatik.uni-bremen.de/) no Competition Rules can be found
(and all links to rules on www.robocup.org and http://www.robocup-us.org/ refer
to this site) at least the sentence "Competition rules must state the duration
of the half-time interval." in law 7 might be removed or modified.

end of proposal for rules change for "Competition Rules"


2. Proposal for a rules change for extra time play and kicks from the penalty
mark:

In 2007th RoboCup Final the case of a draw at the the end of regular game time
of a KO-game came up.
To avoid unscertainty about the procedures to follow after that we ask the
Technical Committee to make a more clear decision about that and to state it in
the rules so that all teams can prepare themselves and their robots for that
case.

We propose the following:

If the game is drawn after the end of the second period and the game needs to
end with a clear winner, extra time will be played (as stated in laws 7 and
10). Before the first half of extra time there will be an interval that must
not exceed 5 minutes.

Periods of Play in extra time
The extra time lasts two equal periods of 5 minutes, unless otherwise mutually
agreed between the referee and the two participating teams. Any agreement to
alter the periods of extra time (for example, to reduce each half to 3 minutes
because of a limited schedule) must be made before the start of play and must
comply with competition rules.

Extra time half-time Interval
Teams are entitled to an interval at half-time. The half-time interval must not
exceed 2 minutes. The duration of the half-time interval may be altered only
with the consent of both teams and the referee.

Timeouts
Each team is allocated two timeouts at the beginning of extra time. A total of
5 minutes is allowed for all timeouts. The number of timeouts and the time not
used in regular game are not added. Timeouts in extra time follow the same
rules as in regular game (stated in law 7).

If the game is drawn after the end of the second period of extra time,
kicks from the penalty mark will be taken to decide which teams wins the game.
Before the first penalty is kicked there will be an interval that must not
exceed 2 minutes. This time is suggested to be used by the teams in dialogue
with the referee and his assistants to check whether the goalie's position is
correct (on the line) and all other rules for penalty can be fullfilled as
stated in law 14.

During the kicks from the penalty mark, a maximum of 2 robots per team is on
the field in order to avoid interference.
The kicks from the penalty mark are taken alternately by the teams until each
team has kicked 5 penalties. If a decision is reached for one team, the kicks
are stopped by the referee. The referee determines which team has to take the
first penalty kick (e.g. by flipping a coin). For all penalties apply the rules
of law 14. A second kick (e.g. if the ball bounces back from the goalie or a
goalpost) or a bounce back from the kicker will not score, as soon as the
kicker touches the ball after he released it the first time the penalty is
over.
During the kicks from the penalty mark no timeout is possible. Robots may be
exchanged between the kicks following the interchange rules of law 3.
As switching sides would cost too much time and would force the teams to touch
their systems both goals are used.
If after 10 kicks no decision is reached each team takes another penalty in the
same order as before. This procedure (one penalty each team) is continued until
a decision is reached.

end of proposals for extra time play and kicks from the penalty mark.


3. Proposal for change in referee-box for the end of game:

As it is stated in the rules in law 5 that the referee enforces the rules of
the game, e.g. the duration of the match. It is also statet in decision 4 of
law 5 that the referee may be assisted by an autonomous or semi-autonomous
application just as the referee-box.

The problem to handle (in our opinion) occures when the referee-box sends a
half-time-signal to the teams when it is half-time (just as well as at the end
of the game). As it is up to the referee to state whether a goal is scored and
he is not as accurate in time measurement (even if his assistant informs him
punctually) it can happen that a robot shoots the ball towards the opponent's
goal, the opponent then stops playing because of the half-time-signal of the
referee-box and the referee decides for goal because of not knowing half-time
was reached. It can even happen that one team stops playing and the other team
continues for some more seconds because of the delay between referee assistant
and referee (as the use of the referee-box' signal is not obligatory for the
teams). As long as computer systems and humans have to coordinate in such a
critical issue as (possibly) milliseconds there will be mistakes which should
be avoided.

Our proposal to avoid this problem is to give the full power about the end of
the periods of play back to the referee. That means that the referee-box sends
an "end of play" not after time is up but after it has been indicated by the
referee that the game is stopped because of it. Therefore we propose to add a
button for "end of half-time" (which can be used at the end of first as well
as second half-time and in extra time as well) which causes the sending of this
special signal. Usually the referee will wait for a clear situation to indicate
that time-over to avoid the problem specified above.

The alternative in our opinion would be to install a system that tracks the ball
and which can tell if a ball has entered the goal in time. This would clearly be
the solution more technical, maybe there is a team or someone who can present us
with such a system.

However to speak with our soccer heart in soccer the time measurement is usually
done not as accurate as e.g. in basketball, where the ball to score has to
leave the hand before the end of the play. In soccer the referee normally lets
the situation find its end, either in scoring or in the clearance by the
defending team. This is why we prefer the first proposal.

The third possibility would contain that all teams are encouraged to ignore the
referee-box' signal about the end of play because of half-time or game end in
order to wait for the referee's signal and to stop their play manually after
that.
This solution would clearly be the hack of the momentary situation and
should not be taken into any closer investigation for long-term.

Just to explain why this problem is definetely not just a formal one: In
Atlanta several goals (We remember at least 3) were scored in the last seconds
before half-time or the end of the match. One goal was scored directly after
the signal for half-time by the referee. Hopefully there were no wrong
decisions about scoring before and after the signal for half-time by the
referee-box, but we can avoid mistakes by merging the control over the end of
the periods at one authority.

end of proposal for change in referee-box for the end of game.


4. Proposal for modification of the goals

As the game is a very fast one and the ball is even faster, it is sometimes
very hard for the referee and his assistants to determine whether the ball
entered the goal, hit the goal-post or even hit the crossbar (as happend in the
game for 3rd place).
In our team we have made very good experience with lining up the goal from
the inner backside with a thin layer (about 8-12mm) of soft foam. Thus we can
actually hear whether the ball entered the goal or not.
I propose this to become at least a hint in the rules how to build a good goal
in order to support the referee team.

end of proposal for modification of the goals


5. Proposal for rules change for dribbler restriction

As some teams are able to control the ball very strongly with their dribblers we
think the dribbler restriction should be changed in some way. As it is nearly
impossible to gain the ball when the dribbler is switched on, we think about
forcing the robots to switch the dribbler off after some time. If a robot is
forced to stop dribbling after e.g. 3-4 seconds ball control and even advanced
ball handling is still possible, but "blocking" the ball is avoided.

That is why we propose: Changing the restriction for the use of a dribbling
device to a maximum time (3-4s). The distance a robot can dribble is not
restricted by the distance itsself, so if a robot is able to drive very fast
when dribbling its up to it's advantage.

end of proposal for rules change for dribbler restriction


6. Proposal for rules change for "force start"

As there is the possibility to change an indirect freekick to a direct shoot
possibility (when waiting for the force start command after 10s) we propose that
there should be a stopped signal before the force start command. This leeds to a
drawn situation for both teams which is in our opinion what the force start is
about.

end of proposal for rules change for "force start"


7. Proposal for rules change for restriction for "Chip Kick"

As the current regulations for irregular chip kick goals cause much confusion to
the referees and teams as well as to the visitors we discussed about a change
concerning that regulation. We think that chip kick goals are very attractive
for visitors, but we also see that too much chip kicking for scoring can be very
destructive for gameplay.

Our Proposal is to invent a new area around the defense area (See pink dots in
the attached graphic). From inside this area, direct chip kick goals are
allowed. From outside this area, no chip kick goals are allowed at all. The
existing rule (which says that a chip kick is no longer a chip kick when the
ball stops bouncing) is erased for reasons of convenience. The new definition
would be: A chip kick is a chip kick until a teammate has touched the ball or a
new situation in play occurs.

end of proposal for rules change for restriction for "Chip Kick"


8. opinions about the new defence area

We have discussed the new defense area and are very satisfied with it. The
points we thought about are:

- The area has still no sharp edges, so the rule that no defender may enter the
area can stay untouched.
- The area has been enlarged slightly, so teams who are able to pass and have
good teamplay are in a good situation, all other teams are encouraged to better
their teamplay.
- The area in front of the goal is not much bigger, the distance between
goalline and defence area border remains the same. That does not lead to more
freedom of attackers who are allowed to enter the defense area (which is good).

We think the new defense area should be accepted as proposed.

end of opinions about the new defence area


9. Proposal for a Challenge: semi-autonomous referee system

As the SSL is a league with a global and total view we think that the
development should go in the direction of a (nearly) total autonomous system.
Therefore a big step would be to have a referee system which is able to analyse
the game in order to make the decisions necessary to control the game.

In the first step we would expect a semi-autonomous referee system which is able
to analyse and to decide. This system would support the referee who should still
be in charge.

In order to push the development and to encourage everybody to think if they
could develop such a system we propose to have a "semi-autonomous referee system
challenge" in Robocup 2008.

end of proposal for a Challenge: semi-autonomous referee system


10. Proposal for a Challenge: Shared vision system

As the field size in SSL keeps growing we think that a shared vision system
would be usefull by means of organization and ressources. Cameras are very
expensive, and on the other hand there is not much development left in vision
systems for SSL, so we think it is not nessecary for every single team to use
their own cameras. The chaos when every team sets their cameras could be avoided
as well.

Similar to the referee system we propose a challenge for robocup 2008 to
encourage development in this field. In a perfect world next year at robocup we
could be presented the prepared systems, chose one for the future and use that
system from 2009 on.

end of proposal for a Challenge: Shared vision system


This is it for today. We would be happy to get a discussion, feedback, comments
and/or other proposals.

So long and thanks for all the fish
Ulfert, B-Smart (Bremen)

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